• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 추계학술대회 논문집
• /
• pp.197-198
• /
• 2008

The forging process produces complicated and designed components in a die at high productivity for mass production and minimizes the machining amount for favorable material utilization; the forging products used at highly stressed sections are well accepted at a wide range of industry such as automobile, aerospace, electric appliance and et cetera. Accordingly, recent R&D activities have been emphasized on improvement of forging die-life and near net shaping technology for cost effectiveness and better performance. Usually closing and consolidation of internal void defects in a ingot is a vital matter when utilized as large forged products. It is important to develop cogging process for improvement of internal soundness without a void defect and cost reduction by solid forging alone with limited press capacity. For experiments of cogging process, hydraulic press with a capacity of 800 ton was used together with a small manipulator which was made for rotation and overlapping of a billet. Size of a void was categorized into two types; ${\phi}$ 6.0 mm and ${\phi}$ 9.0 mm to investigate the change of closing and consolidation of void defects existed in the large ingot during the cogging process. In addition for forming experiment of piston grown air drop hammer with a capacity of 16 ton was used. The experiment with piston crown was carried out to show the formability and void closing status. In this paper systematic configuration for closing process of void defects were expressed based on this experiment results in the cogging process. Also forging defects through forming process for piston crown was improved using the experiment results and FE analysis. Consequently this paper deals with the effect of radial parameters in cogging process on a void closure far large forged products and formability of piston crown.

• 디지털콘텐츠학회 논문지
• /
• 제19권6호
• /
• pp.1043-1050
• /
• 2018

식문화 편의경제 시대의 본격화로 인해 간편하고 편리하게 식사를 해결하려는 소비 트렌드가 확산됨에 따라 각 식품업체에서는 더 나은 서비스를 제공하기 위해 다방면으로 노력하고 있다. 이러한 변화와 함께 주문방법에 있어서도 다양한 방식을 채택하여 신속하고 간편한 주문이 가능해졌다. 특히, 계산을 위한 대기열의 단축, 인건비의 절약, 업무프로세스의 원활함 등 여러 장점을 지닌 키오스크 주문 시스템의 도입은 최근 적극적으로 확산되고 있다. 키오스크 시스템이 주문뿐만 아니라 체계적인 콘텐츠를 제공하고 타 기업과 차별화 된 아이덴티티를 고려한 인터페이스 디자인을 제공한다면 브랜드 이미지 향상과 더불어 고객서비스 전략으로 활용 가능할 것이다. 이에 본 연구에서는 패스트푸드점 내 키오스크의 구조 및 콘텐츠, 그리고 GUI 디자인에 관해 분석하고 사용자 설문조사를 통해 키오스크의 사용 실태 및 디자인 선호도를 조사함으로써 사용자에게 보다 편리한 사용성을 제공하고 만족도를 높일 수 있는 효과적인 상호작용을 위한 키오스크 GUI 디자인 방안에 관해 연구한다.

• 수산해양기술연구
• /
• 제56권3호
• /
• pp.246-257
• /
• 2020

According to the statistics of KMST (2010~2019), 68.5% of marine casualties have been occurred in fishing boats in the last 10 years. Although the incidence rate of annual average per ship is 10.4% for merchant ships and 2.3% for fishing boats, it is necessary to first reduce the marine casualties of fishing boats in order to reduce the occurrence of the whole marine casualty, considering that the number of registered fishing boats are 86.5% of the total. In this study, the top 10 fishing types with high occurring marine casualties in the past 10 years were selected using the statistics of KMST. Then, the causes of the marine casualties, focusing on the collision, were analyzed and counterplan were suggested. The biggest marine casualty that the top 10 fishing types have caused in the past 10 years was a collision, accounting for 71.7% of the total, and the rest were less than 10.0% each. Also, it was found that the biggest environment and cause of the collision were due to human factors such as poor look out or negligence of duty. Eventually, it was concluded that a reduction in the human factors for the causes basically, could lower the incidence of the marine casualties. Therefore, if the continuous and systematic correcting education of the attitude toward the ship operating of seafarers could conducted with the focus on the main human factors, the whole marine casualties will be expected to decrease gradually.

• 한국정밀공학회지
• /
• 제3권3호
• /
• pp.40-71
• /
• 1986

By developing a computer program for the systematic design of worm gears, the design formulae and tables of AGMA, JGMA, BS and DIN are analized and compared. The computer program can be used on micro-computers. According to the input data of the reduction ratio, the center distance. the driving torque and the material as design parameters, the program calculate the most efficient worm gear dimension. The variation of the design parameters and other empirical coefficients in case of resulting an inadequate design gear dimension can be easily modified throuth the way of interactive method between the user and the monitoring system of computer. A proposal of the standardization of worm gears was made in which a standard module according to the DIN 323 standard series number was applied. For the more exact and effective calculation of the stress concentration and the deformation of gear teeth, a computer program using the boundary element method is also developed. Even the strength of the special gear shape such as Niemann's "Cavex" gear can be calculated in a short CPU-time. The most effort of this study has been layed on the developing a computer program for the correction of a tooth profile and face width which is most important design factor for an exact and wide teeth contacts under loads, especially by great and wide gears. For this purpose were investigated the tooth stiffness, the mesh interferences and the kinematics and the dynamics of gear mesh. The deflection and the deformation of the gear shaft due to the loads acting on gear and shaft were aslo considered. Some examples have shown the sufficient good status of teeth contact in which the correction of the tooth profile and face width were accomplished due to the calculated results.d results.

• 조명전기설비학회논문지
• /
• 제14권3호
• /
• pp.49-58
• /
• 2000

본 논문에서는 FACTS(Flexible AC Transnission System)로 분류되는 여라 기기중 기존의 전압제어 및 무효 전력보상기들이 가지고 있는 바속응성과 불연속성 문제를 해결해줄 수 있는 정지형 무효전력 보상가(Static Var Compensator : SVC)를 포함한 전력계통에 신경회로망 제어기를 적용하여 안정화에 관하여 연구하였다. 제안된 신경회로망 제어기는 오차와 오차변화량을 입력하는 오차역전과 학습 알고리즘을 사용하고, 학습시간올 단축하기 위해 모멘텀 방법을 사용하였다. 제안된 방법의 강인섬을 입증하기 위해 중부하시 및 정상부하시에 초기 전력을 변동시킨 경우와 초기에 회천자각을 변동시킨 경우에 대하여 시스렘의 회전자각, 각속도 편차 특성 및 단 자전압의 동특성을 고찰하여 다른 시스템보다 응답특성이 우수합을 보였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
• /
• pp.275-278
• /
• 2006

[ $CH_4-He/Air$ ] 대향류 확산화염의 저 화염 신장율에서 진동 불안정성에 관하여 실험적으로 연구하였다. 저 화염 신장율에서 진동 불안정은 Le가 1보다 클 때 소화한계 부근에서 발행하고 측면방향 열손실이 중요한 역할을 한다. 화염이 진동할 때 화염의 형태는 전진하거나 후퇴하는 edge flame이고 진동의 동적거동은 성장, 조화 그리고 감쇠 진동 모드 세 가지로 나타났다. 전체 화염 신장율이 감소하면 진동의 진폭은 커지게 되는데 이는 화염의 크기가 감소하게 되어 측면 열손실이 증가하였기 때문이다. 저 화염 신장율에서 edge flame의 진동 불안정성은 Le 뿐만 아니라 복사와 측면 열손실도 밀접한 관계가 있다.

• 한국철도학회논문집
• /
• 제11권1호
• /
• pp.107-113
• /
• 2008

최근 생애주기비용 분석이 사회기반 시설물 경제성 평가 분야의 필수적 방법으로 대두됨에 따라 체계적이고 합리적인 방법으로 각 시설물의 생애주기비용을 산정하기 위한 노력이 진행되고 있다. 합리적인 생애주기비용 분석을 위해서는 초기비용 뿐만 아니라 유지관리 비용의 예측이 필요하나 국내에서는 고속철도 구간에 강교량을 가설한지 얼마 되지 않았기 때문에 이에 대한 유지관리 특성 등을 파악하고 있지 못한 실정이다. 이에 본 연구에서는 고속철도 소수주형교의 계측데이터와 Rahgozar 등이 제안한 부식열화를 고려한 피로강도감소계수 및 Miner 손상누적법칙을 이용하여 강교량의 주된 열화의 요인이 되는 부식과 피로의 손상을 고려한 체계신뢰성해석을 실시하였다. 이 체계신뢰성 해석결과를 바탕으로 고속철도 소수주형교의 설계단계 생애주기비용 분석 모델을 제안하였다.

• 한국건축시공학회지
• /
• 제6권1호
• /
• pp.87-91
• /
• 2006

Since water leakage and cracks are not the source of serious problems such as long-term lowering of performance and durability of a stricture, including damages to operating facilities of a structure, damages to internal finishing materials, exhibition, and goods, and pollution of residential environment, they might have led to development of positive coping skills; however, an instant loss of lives or property due to earthquake, explosion, typhoon, or a fire was indeed neglected. In these days, repair materials for leakage cannot help but being taken in temporary way without any noticeable countermeasure. This kind of repair is socially criticized many times that is defective construction even if this costs a lot. It was not arrange the standard for construction methods of sealer of injection type for leakage maintenance, even it has been used various type of construction methods for leakage part. In conclusion, we suggest that the construction methods of sealer of injection type for leakage maintenance for leakage to establish the leakage repairing technology as increase of structure demand. Therefore, it would be possible to provide a stage-by-stage solution by developing systematic research activities among the industry, schools, and research institutes to spread maintenance management techniques globally through technical solution to water leakage and cracks, acquisition of structural safety with prolonged durability for life cycle, reduction of water leakage repair expense s, and so on.

• 대한치과의사협회지
• /
• 제54권6호
• /
• pp.429-437
• /
• 2016

Objectives: Photodynamic therapy has been proven to promote additional clinical and microbiological benefits in the treatment of chronic periodontitis and aggressive periodontitis. The purpose of this study is to assess the effectiveness of the photodynamic therapy for patient with periodontitis. Methods: We searched the eight Korean databases and Ovid-MEDLINE, Ovid-EMBASE, Cochrane Library. Total 300 studies were searched and 13 studies were included in the final assessment. Each of the stages from literature search and extraction of data were carried out independently by 2 researchers. We used tools of Scottish Intercollegiate Guidelines Networks for assessment of the quality of studies. Results: The safety of the photodynamic therapy was assessed by bleeding. The effectiveness of the photodynamic therapy was assessed by the reduction of Probing pocket depth (PPD) and the gain of Clinical attachment level (CAL). The mean difference of PPD was 0.46(95% CI 0.09~0.82), (p=.01).). The mean difference of CAL was ?0.49(95% CI ?1.12~0.14), (p=.13). Conclusion: The additional use of $^{\circ}{\infty}$Antimicrobial Photodynamic Therapy for Periodontitis$^{\circ}{\pm}$ caused hemorrhage to similar extents to conventional treatment modalities, where scaling and root planing are solely performed, in patients with periodontitis who are expected to have a lower degree of treatment response to non-surgical or surgical periodontal therapies (implant or refractory periodontitis) and those where there is a concern for the possible occurrence of antimicrobial side effects or resistance. This indicates that there are no problems with its safety. But there were no consistent reports about the effects of the additional use of photodynamic therapy. This led to a decision that the safety and efficacy of the current technology deserve further studies (Recommendation rating of A, Classification of technology II-a).

• 한국환경과학회지
• /
• 제20권4호
• /
• pp.435-442
• /
• 2011

In this study, to investigate the effects of herb aroma components, the BDI test was performed with the 124 students of the Youngdong University and the subjects whose score was 16 or higher were selected and allocated to the herb-extracted aroma-treated group and the non-treated group, 27 and 10 students for each group. The BDI and SDS tests were carried out at each stage (before and after the treatment, 10 days later and 30 days later). The result showed that the pre-treatment BDI test result was significantly different from all those of the post-treatment test, and the tests after 10 days and 30 days in the aroma-treated group. In the SDS test, the pre-treatment test result was significantly different from the results of the post-treatment test and the test after 10 days, while it was not significantly different from the result of the test after 30 days. Additionally, to verify whether the change within the group is larger than that by natural recovery or not, ANCOVA was performed with respect to the difference in the pre-treatment test score between the groups depending on whether the treatment was given or not, having the SDS pre-treatment score as the covariate, and the result showed that the post-treatment test scores were significantly different. Thus, it was verified that, if the SDS test score is considered as the depression indicator, the effect of aromatherapy was greater than the change by natural recovery. The difference in the post-treatment test score was analyzed depending on whether the treatment was given or not, having the BDI pre-treatment test score as the control variable, and the result showed that the post-treatment test scores were not significantly different. Based on such a theoretical verification, it is assumed that the nature-friendly treatment method using herb aroma components can be a great help in suppressing depression. Therefore, it is expected that herb aroma components can provide systematic therapeutic effect on the suppression of depression.